Are my o2's cycling ok? Log attached - 3000GT/Stealth International Message Center

Manj · 08-12-2008, 08:59 PM

Hey guys,

I've just got my car re-tuned but it's running rich. The tuner is unable to get the fuel trim high and fuel trim low at 100% because he says my o2's are wrong.
I'm using the eManage Blue to tune the car, would the o2's cause this problem for not allowing the eManage to control the fuel??

Drove the car for 5 minutes before I took the log. The log was taken in 3rd gear and the RPMS were between 2500 and 2700.
Please advise..

brutten · 08-12-2008, 10:11 PM

front does not look like it is cycling correctly. Could be a bad sensor or something else.

Rom3BreaK · 08-12-2008, 10:27 PM

Yeah, the front one's a bit lazy. I can't believe how rich you're running though which makes me think something else is going on. You should see my logs, the rear O2 sensor hardly ever cycles and it often shoots up above 1.0V and stays there..and sometimes the front doesn't cycle. The worst I've seen was 85% fuel trims though. Oh and that is with a NEW rear O2. I've actually asked here about it and have yet to get a response, I have no idea what's going on with it....

What does it mean when the sensors flat-line like that toward the end of the logs (mine do it also)?

Something else I've thought about is that it's probably best to log the O2's after the car has been running for a little while due to open/closed loop modes which is explained here under "How does and O2 sensor work?" Oxygen Sensor Information

lawdogg · 08-13-2008, 06:07 AM

Just making sure your car was warmed up before taking that log.

Manj · 08-13-2008, 08:50 AM

I drove the car for 5 minutes before taking the log.
The log was taken in 3rd gear and the RPMS were between 2500 and 2700.

BlackStealth · 08-13-2008, 01:27 PM

Either your front o2 sensor is broken, or perhaps one of your front fuel injectors is defective and squirting too much fuel, OR the tune is way too rich.

Manj · 08-13-2008, 03:30 PM

Quote:

Originally Posted by BlackStealth

Either your front o2 sensor is broken, or perhaps one of your front fuel injectors is defective and squirting too much fuel, OR the tune is way too rich.

The injector are Denso 660's which I got used off the forum. The seller said they only had a few thousand miles on them. I hope he didn't lie.

The tuner was unable to tune the eManage properly cause he said the o2's would not let him because they kept dumping more fuel. Would this make sense?

BlackStealth · 08-13-2008, 04:19 PM

You do realize you can unplug the o2 sensor harnesses and verify that theory pretty quick.

Manj · 08-13-2008, 04:48 PM

Quote:

Originally Posted by BlackStealth

You do realize you can unplug the o2 sensor harnesses and verify that theory pretty quick.

How can I test this theory? That would be a great help

BlackStealth · 08-13-2008, 06:57 PM

When you unplug your o2 sensors, your fuel trims will freeze and blaming the o2 sensors for running rich will be invalid. Making adjustments on the blue emanage will be unhindered.

You could also experiment unplugging your battery terminal and reset your ECU, all fuel trims will reset back to 100.

08-12-2008, 08:59 PM	#1 (permalink)
Manj Forum Member Join Date: Mar 2003 Location: Toronto Drives: 94 RT TT Trader Rating: (5)	Are my o2's cycling ok? Log attached Hey guys, I've just got my car re-tuned but it's running rich. The tuner is unable to get the fuel trim high and fuel trim low at 100% because he says my o2's are wrong. I'm using the eManage Blue to tune the car, would the o2's cause this problem for not allowing the eManage to control the fuel?? Drove the car for 5 minutes before I took the log. The log was taken in 3rd gear and the RPMS were between 2500 and 2700. Please advise.. __________________ Manj's Wanna-Be GTO Complete Custom Body Kit and Paint (Viper Red with 3 pearls), 19T-HL with 7* clip, FMIC, Greddy BOV , eManage Blue, Denso 660's, 18" Kosie Sniper Rims, HKS Intake, 3" Downpipe, Testpipe and MagnaFlow Exhaust system, ACT Clutch, Eibach Springs, NGK Plugs and Wires, Autometer boost and Air/Fuel gauges, Supra Fuel Pump, EGR Block Off Plates, Pioneer Deck, 3 Boswick Amps, 2 12" Boswick Subs, JL Front and Mids...... Can't forget the Bat Man floor mats Last edited by Manj : 08-13-2008 at 10:05 AM.

08-12-2008, 10:11 PM	#2 (permalink)
brutten Verified Seller Join Date: Apr 2003 Location: 46° N 96° W Drives: Several VR4's Trader Rating: (25)	Re: Are my o2's cycling ok? Log attached front does not look like it is cycling correctly. Could be a bad sensor or something else.

08-12-2008, 10:27 PM	#3 (permalink)
Rom3BreaK Verified Seller Join Date: May 2007 Location: Northern CT Drives: Mitsu 92 VR4 Trader Rating: (7)	Re: Are my o2's cycling ok? Log attached Yeah, the front one's a bit lazy. I can't believe how rich you're running though which makes me think something else is going on. You should see my logs, the rear O2 sensor hardly ever cycles and it often shoots up above 1.0V and stays there..and sometimes the front doesn't cycle. The worst I've seen was 85% fuel trims though. Oh and that is with a NEW rear O2. I've actually asked here about it and have yet to get a response, I have no idea what's going on with it.... What does it mean when the sensors flat-line like that toward the end of the logs (mine do it also)? Something else I've thought about is that it's probably best to log the O2's after the car has been running for a little while due to open/closed loop modes which is explained here under "How does and O2 sensor work?" Oxygen Sensor Information __________________ 1992 VR4, Java Black Pearl paint ('04 STI) with combo '92/'96/'99 custom front end, Fittipaldi Force wheels, RPS Max pressure plate with street disk, P.I.T. BCU+ EBC, Gutted pre-cats, Greddy type RS BOV, K&N intake. Currently working a minimum wage job to get my 3s back to 100% (again) as well as pay for tuition....AKA the stereotypical proud 3si member. Last edited by Rom3BreaK : 08-12-2008 at 10:36 PM.

08-13-2008, 06:07 AM	#4 (permalink)
lawdogg Here for the tuna. Join Date: Jul 2003 Location: Williamsport, PA Drives: The Speed Limit Trader Rating: (66)	Re: Are my o2's cycling ok? Log attached Just making sure your car was warmed up before taking that log. __________________ 94 VR-4: 11.8 @ 116, 17psi, pump, 13Ts Nov 2008 ROTM

08-13-2008, 08:50 AM	#5 (permalink)
Manj Forum Member Join Date: Mar 2003 Location: Toronto Drives: 94 RT TT Trader Rating: (5)	Re: Are my o2's cycling ok? Log attached I drove the car for 5 minutes before taking the log. The log was taken in 3rd gear and the RPMS were between 2500 and 2700.

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08-13-2008, 01:27 PM	#6 (permalink)
BlackStealth Verified Seller Join Date: Apr 2000 Drives: 93 RT/TT Trader Rating: (162)	Re: Are my o2's cycling ok? Log attached Either your front o2 sensor is broken, or perhaps one of your front fuel injectors is defective and squirting too much fuel, OR the tune is way too rich.

08-13-2008, 04:19 PM	#8 (permalink)
BlackStealth Verified Seller Join Date: Apr 2000 Drives: 93 RT/TT Trader Rating: (162)	Re: Are my o2's cycling ok? Log attached You do realize you can unplug the o2 sensor harnesses and verify that theory pretty quick.

08-13-2008, 06:57 PM	#10 (permalink)
BlackStealth Verified Seller Join Date: Apr 2000 Drives: 93 RT/TT Trader Rating: (162)	Re: Are my o2's cycling ok? Log attached When you unplug your o2 sensors, your fuel trims will freeze and blaming the o2 sensors for running rich will be invalid. Making adjustments on the blue emanage will be unhindered. You could also experiment unplugging your battery terminal and reset your ECU, all fuel trims will reset back to 100.